Thanks to Richard Overthrow for putting me onto this. I’ve always said that there is more value to allotments than appears on the surface. Usually I’ve talked about social and health benefits and I have even been known to mention food miles but one thing I’ve not really thought about is the quality or health of the soil.
Modern agriculture is efficient in terms of crops produced per man hour because it uses a lot of machinery. Giant tractors that can pull huge loads are all well and good but they compact the soil with their weight.
High use of artificial fertilisers push plant growth but do nothing positive, and lots of negative, to the eco-system of the soil. Those bacteria and microscopic organisms that work together with the plants are reduced in number. Imagine the soil as a person on a diet of fast foods, filled up on pizza and burgers with no room left for the 5-a-day vegetables.
Finally, modern agricultural practice may distribute some animal manure (most often as slurry) back onto the land but there’s no compost making program. So precious little humus, organic matter, in the soil.
Humus is a bit like fibre in the diet. It doesn’t add nutrients as such but it keeps the system open and working. Humus in the soil holds water during drought and absorbs it during flood.
Sustainable Production depends on Soil Quality
In a period of rising food demand, it’s self evident that sustainable production will maintain the quality of the soil or better still, improve it to maximise its production potential.
This is where allotments come in – an increase in urban allotments could help us meet the rising demand for food throughout the world, without damaging the Earth’s soils, according to new research from the University of Sheffield.
Dr Jill Edmondson from the University’s Department of Animal and Plant Sciences, has found that soils under Britain’s allotments are significantly healthier than soils that have been intensively farmed.
Ecologist Dr Edmondson took soil samples from 27 plots on 15 allotment sites from across the city of Leicester. She also sampled soils from local parks, gardens and surrounding agricultural land and used these to measure a range of soil properties, including soil organic carbon levels, total nitrogen, and the ratio between carbon and nitrogen (which are all directly related to the amount and quality of organic matter in the soil) as well as soil bulk density, an indicator of soil compaction.
Allotment soil found to be significantly healthier.
The results won’t surprise allotment holders and home veg growers. Compared with local arable fields, the allotment soil was found to be significantly healthier. Allotment soil had 32 per cent more organic carbon, 36 per cent higher carbon to nitrogen ratios, 25 per cent higher nitrogen and was significantly less compacted.
Dr Edmondson, said:
“We found remarkable differences in soil quality between allotments and arable fields. Our study shows how effectively own-growers manage soils, and it demonstrates how much modern agricultural practices damage soils.”
Allotment holders are able to produce good food yields without sacrificing soil quality because they use sustainable management techniques. For example, 95 per cent of allotment holders compost their allotment waste, so they recycle nutrients and carbon back to their soil more effectively.
Dr Edmondson also said
“An estimated 800 million city dwellers across the world participate in urban food production, which makes a vital contribution to food security. Our results suggest that in order to protect our soils, planning and policy making should promote urban own-growing rather than further intensification of conventional agriculture as a more sustainable way of meeting increasing food demand.”
When you consider that during WW2 10% of Britain’s home food production came from the 1% of the land which was the allotments and gardens turned to food production in the ‘Dig for Victory’ campaign, her views make a lot of sense.
Hopefully our government can see beyond the next election to the future when Britain will need to feed its population in a situation of rising costs and reducing availability of food and hang onto allotments. Because even if they’re not fully utilised today, in 20 years time we’re likely to need every square inch of land.
Dr Edmondson’s study “Urban cultivation in allotments maintains soil qualities adversely affected by conventional agriculture” has been published in the Journal of Applied Ecology.